Apparatus for applying adhesive seams to webs

ABSTRACT

Apparatus is disclosed for applying adhesive seams to high speed webs for securing them together. An even coating of the adhesive, heated, if necessary is applied to a rotating gravure roll; and one web is fed in partial wrapping engagement about a rotating plate cylinder having a raised transfer bar fixed to its periphery. As the rolls rotate, the transfer bar engages the traveling web and elevates it above the surface of the plate cylinder and into contact with the gravure roll to deposit a seam of adhesive to the outer convex surface of the web according to the pattern defined by the transfer bar. The two webs are then pressed together and secured by the adhesive. Adhesive seams may also be applied to both webs, if desired, with the applied seams being in register with each other, then presses together.

July 4, 1972 D. NYSTRAND 3,674,608

APPARATUS FOR APPLYING ADHESIVE SEAMS TO WEBS Filed July 6, 1970 FIG. I

INVENTOR: ERNST DANIEL NYSTRAND ATT'YS United States Patent US. Cl. 156-553 3 Claims ABSTRACT OF THE DISCLOSURE Apparatus is disclosed for applying adhesive seams to high speed webs for securing them together. An even coating of the adhesive, heated, if necessary is applied to a rotating gravure roll; and one web is fed in partial wrapping engagement about a rotating plate cylinder having a raised transfer bar fixed to its periphery. As the rolls rotate, the transfer bar engages the traveling web and BACKGROUND OF THE INVENTION (1) Field of the invention The present invention relates to applying adhesive to webs; and more particularly, it relates to the application of adhesive seams to webs traveling at high speeds. The invention has particular advantage in applying adhesive seams transverse to the direction of travel of the web.

'Normally, after an adhesive seam is applied to one or both of two webs they will be brought into contact under pressure to secure the webs together along the adhesive seams.

Techniques for applying adhesive seams in longitudinal as well as transverse directions in order to secure two webs together along the seams are used in the production of disposable articles, such as pillow cases. The webs in this case are paper; however, the types of adhesives compatible with the present system may be used on tissue, polyethylene, SRM, and other non-woven materials.

(2) Prior techniques Many of the materials used in this field require adhesives which melt only at high temperatures (so-called hot melt adhesives). Normally, in the formation of longitudinal seams, a bead of melted adhesive is extruded onto one of the webs. It is possible to extrude a similar bead of adhesive for the forming of transverse seams, but it is not practical for high speed application. It will be appreciated by persons skilled in the art that it is desirable to form the adhesive seams in disposable articles at very high speeds.

Printing of the transverse adhesive seams has been tried, but conventional printing techniques have failed because of the particular characteristics of the hot melt adhesives and because of the need to maintain the adhesive within very narrow and well-defined temperature limits for proper application.

The use of transverse printing plates made of rubber or other flexible material coated with the adhesive and then pressed against the web has been found to be unsatisfactory because the plate becomes filled with lint from the web. Another difiiculty with rubber printing plates is that the surface of the printing plate must be maintained 3,674,608 Patented July 4, 1972 at the required temperature, and this becomes difficult to achieve for operation at different speeds. Conventional gravure systems have also been tried, but it is very diflicult to keep the gravure cylinder completely free from adhesive in the areas in which it is not desired to transfer the adhesive.

SUMMARY In the present system adhesive is applied to a rotating gravure roll which has a full print surface-that is, the adhesive is applied to the entire usable surface of the gravure roll. Preferably, a small fountain of the adhesive with a reverse doctor blade is used. One of the webs to be secured together is fed in partial wrapping engagement about a rotating plate cylinder having a raised transfer bar fixed to its periphery. As the rolls rotate, the transfer bar (which may be arranged in any desired pattern so as to provide either transverse or longitudinal seams or even inclined seams) engages the traveling web and elevates it above the surface of the plate cylinder and into contact with the gravure roll to transfer the adhesive to the outer convex surface of the traveling web according to the pattern defined by the transfer bar.

The two webs may then be brought together and pressed so that they become secured by the adhesive seam. In certain applications where it is desired, the adhesive seams may be applied to both webs in register. When required, the fountain containing the adhesive and the gravure roll are both heated by passing a liquid through them.

The transfer bar on the plate cylinder may also be used to apply the pressure for bonding the web bearing the adhesive seam to a second web brought into contact with it. The transfer bar, being on the plate cylinder, stays clean because it never comes into contact with the adhesive.

I have also found that the system works equally well with cold adhesives. Other features and advantages of the present invention will be apparent to persons skilled in the art from the following detailed description of a preferred embodiment together with the accompanying drawing.

THE DRAWING FIG. 1 is a diagrammatic view, taken from the side, of a system incorporating the present invention;

FIG. 2 is a diagrammatic view of a modified version of the system wherein adhesive is applied to two webs.

DETAILED DESCRIPTION Turning first to'the diagrammatic showing of FIG. 1, reference numeral 10 designates a first web being unwound from a source designated 11. Numeral 12 designates a second web being unwound from a source 13.

The web 10 is fed around an idler roller 14 and into partial wrapping engagement with a plate cylinder 15. The plate cylinder 15 has attached to its peripheral surface a transverse transfer bar or plate 16. In the illustrated embodiment, the transfer bar 16 extends in a direction parallel to the axis of the cylinder 15', and a wide range of materials may be used such as stainless steel or other hard metals as well as resilient materials such as rubber, etc.

The plate cylinder 15 rotates in a clockwise direction, as shown in the drawing. Also rotatably mounted adjacent the plate cylinder 15 is a gravure roll 17 mounted for rotation in a counterclockwise direction and spaced from the plate cylinder 15 such that the transfer bar 16 will elevate the web 10 as the rolls rotate and bring the web into contact with the surface of the gravure roll 17.

The gravure roll 17 has a full print surface-that is, its surface is such that it will be covered everywhere with adhesive so that wherever the web contacts the gravure roll, it will pick up adhesive. Located adjacent the gravure roll 17 is an adhesive pot or fountain generally designated 18 and containing a supply of adhesive 19 contacting the surface of the gravure roll 17. A doctor blade 20 located on the fountain 18 and inclined at a reversed angle relative to the direction of rotation of the periphery of the gravure roll 17 is located downstream of the position of contact of the gravure roll with the adhesive 19. Thus, the doctor blade 17 provides a uniform layer of adhesive on the full print gravure plate.

It will be thus appreciated that the coating of adhesive will be applied to the exterior (i.e. convex) surface of the web as it is elevated by the transfer bar 16 to come into contact with the surface of the gravure roll 17. The transfer bar 16 of the illustration will provide a complete transverse seam or ribbon of adhesive; however, it has been found that the pattern of the transfer bar may be varied to any desired pattern required for the adhesive seam. For example, if it is desired, the transfer bar 16 could be in the form of peripheral rings extending about the cylindrical surface of the plate cylinder to provide continuous longitudinal seams.

Located above the plate cylinder 15 is a press roll 22 rotating in a counterclockwise direction. The web 12 is fed about idler rollers 23 and 24 into partial wrapping engagement about the cylindrical surface of the press roll 22. The feeding of the webs 10 and 12 is synchronized so that the webs are traveling at the same speed. As the plate roll 25 rotates so that the transfer bar 16 is in an upright position, the adhesive seam on the outside of the web 10 will contact and be pressed against the outer surface of the web 12, while both are traveling at high speed; and I have found that one is able to run the webs at a speed of up to 500 feet per minute with satisfactory results. The laminated webs, designated by reference numeral 26 are then fed over an idler roller 27 and into the nip 28 of two nip rollers 29 and 30 where they may be further pressed, if desired.

Turning now to FIG. 2, there is shown a diagrammatic view of a modification wherein a seam of adhesive is applied to both webs prior to laminating. A first web designated 110 is fed over the idler rollers 111, 112 and 113 into partial wrapping engagement with a plate cylinder designated by reference numeral 115 and including a raised transfer bar 116. A second web 117 is fed over an idler roller 118 and into partial wrapping engagement with a second plate cylinder 119 provided with a raised transfer bar 120. The plate cylinder 115 rotates in a counterclockwise direction whereas the plate cylinder 119 rotates in a clockwise direction; and the two are rotated in synchronism so that their respective transfer bars 116 and 120 contact during each revolution. Associated with the plate cylinder 115 is a full print gravure roll 122 provided with a source of adhesive generally designated 123. The plate cylinder 119 is provided with an associated full print gravure roll 126 which, in turn, is provided with a source of adhesive generally designated 127. The transfer bar 116 engages the inner surface of the web 110 and raises it to bring it into contact with the smooth coating of adhesive on the exterior of the gravure roll 122. Likewise, the raised surface of the transfer bar 120 engages the inner surface of the web 117 to elevate it into contact with the rotating gravure roll 126. Each web thereby has a transverse seam of adhesive; and these two are brought together in the nip, generally designated by the reference numeral 130 between the two plate cylinders 115 and 119, where they are pressed together. Thereafter, the laminated Webs are fed about an idler roll 131 4 and between two nip rolls 132 and 133, if desired. A previously-deposited double layer of adhesive between the webs and 117 is designated by reference numeral 135 in FIG. 3.

I have found it desirable to apply a smaller amount of adhesive on each web to be bonded with the seams in register, as disclosed in connection with the embodiment of FIG. 2. This is particularly advantageous when strikethrough of the adhesive relative to the web is a factor. As has already been mentioned, although the system Is particularly advantageous for applying transverse seams of adhesive to webs traveling at high speed, it has also been found to yield excellent results for many kinds of patterns, each pattern being represented by its own transfer bar.

I claim:

1. In a system for uniting webs along spaced-apart generally transverse lines, the combination of a plate cylinder with a raised generally transversely elongated transfer surface rotating about an axis, source means feeding a web in partial wrapping engagement about said plate cylinder, nip roll means operably associated with said plate cylinder and in the path of travel of said web as it leaves said plate cylinder to tension said web between said nip roll means and said source means, one surface of said web engaging said transfer surface to raise selective portions of said web above the surface of said cylinder, and a gravure roll coated with a uniform layer of adhesive and rotating in spaced relation with said plate cylinder for contacting the portions of said web elevated by said transfer surface to apply an adhesive ribbon generally transversely thereto.

2. The system of claim 1 further comprising second source means for feeding a second web in synchronism with said first web, a press roll rotating adjacent said plate cylinder and receiving said second web, the spacing of said plate cylinder and press roll causing said adhesive ribbon to contact said press roll under pressure of said transfer surface.

3. The system of claim 1 further comprising a second plate cylinder with a raised transfer surface complementary to the transfer surface of the first plate cylinder, second source means feeding a second web into partial wrapping engagement about said second plate cylinder, one surface of said second web engaging the transfer surface of said second plate cylinder to raise selected portions of said second web above the surface of said second plate cylinder, a second gravure roll coated with a uniform layer of adhesive and rotating in spaced relation with said second plate cylinder for contacting the portions of the second web elevated by said transfer surfaces of said second plate cylinder to apply an adhesive ribbon thereto, said first and second plate cylinders cooperating to bring said webs together with their associated adhesive ribbons in register.

References Cited UNITED STATES PATENTS 1,837,841 12/1931 Swift 156-543 2,742,080 4/1956 Cloud 156-549 2,275,157 3/1942 Morgan 156295 3,408,248 10/1968 Maass 156277 BENJAMIN A. BORCHELT, Primary Examiner J. V. DORAMUS, Assistant Examiner US. Cl. X.R. 156-324, 548 

